Elastic and thermodynamic properties of the Ti2AlNb orthorhombic phase from first-principles calculations

Ti2AlNb-based alloy with a dominated orthorhombic phase is one of the most promising high-temperature structural materials. In this work, the equilibrium volume, elastic, and thermodynamic properties of the ordered O phase with stoichiometric Ti2AlNb were predicted under different temperatures using first-principles calculations based on density functional theory combined with quasi-harmonic approximation (QHA). With the increase of temperature from 0 to 1300 K, the elastic properties decrease moderately and the bonding strength weakens slightly. The intrinsic properties of the Ti2AlNb O phase are ductile at all temperature considered. In order to explore the evolution mechanism of the temperature-dependent elastic properties further, the density of state (DOS) has been analyzed. The stoichiometric Ti2AlNb O phase shows good high-temperature mechanical and thermal stability, which is a kind of potential high-temperature alloy applied in aeronautics industries. (C) 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim